The present invention relates to the field of perfumery. It relates, more particularly, to esters derived from 1-(3,3-dimethyl-1-cyclohexyl)-1-ethanol which have remarkable odor properties.
We have found that the esters according to the present invention and as defined in the formula (I) below, show useful and prized odor properties and that, as a result, they can be used for the preparation of perfumes, perfuming compositions and perfumed articles. They are employed in order to confer musky type odor effects.
In the field of the synthesis of compounds having musky odors, there has been great activity for the last ten years, resulting from the need to find novel musky odor compounds which can replace certain compounds of widespread use in perfumery and which use is becoming more and more restricted due to toxicological and ecological reasons. The esters according to the present invention are products which fulfil the requirements for perfuming compounds, and they are capable of replacing the above-mentioned known compounds.
The prior art, in particular the application DE-OS 1 923 223, discloses certain esters derived from 1-(3,3-dimethyl-1-cyclohexyl)-ethanol. However, there is no mention of a musky odor from any of the compounds disclosed. The olfactive character of the known compounds is generally described as being of the floral-woody type.
On the other hand, U.S. Pat. No. 5,166,412 discloses compounds of the type 
wherein R is an alkyl group from C1 to C3, and which show an odor of the musky type characterized by an intense note of the type ambrette seeds, fruity-pear, reminiscent of the odor of Williams pears.
We have now surprisingly found that the compounds described by formula (I) defined below have musky odors which are quite distinct from those of the compounds of the above formula (II), and which are very much appreciated in perfumery.
The object of the present invention is therefore to provide new compounds which are useful as perfume ingredients, to impart odors of the musky type.
This object is attained by the compounds of formula 
in which the symbols R1, R2, R3 and R4 represent independently from each other a hydrogen atom or a methyl or ethyl group, the symbol X represents an oxygen atom or an alkylene group of formula 
in which n is an integer from 1 to 3, the symbols R6 and R7 represent each a hydrogen atom or a methyl or ethyl group, and R5 represents an alkyl or alkoxy group from C1 to C4, linear or branched, an alkenyl group from C2 to C4, linear or branched, or a group of formula 
in which Y has the same meaning as X and R8 is a linear or branched alkyl group from C1 to C4 or a linear or branched alkenyl group from C2 to C4.
According to a preferred embodiment of the invention, there will be used compounds of the general formula (III) 
in which X is an oxygen atom or an unsubstituted methylene or ethylene group and R5 is a group as defined in formula (I) and having 1 to 3 carbon atoms.
The esters of the above formulae (I) and (III) are novel compounds.
Another object of the invention is the use of the compounds of the above formulae in perfumery, as well as the perfumes perfuming compositions and perfumed articles containing these compounds.
The compounds of the invention show musky odor notes in which a slight fruity-ambrette connotation is found, which however is clearly less pronounced than in the compounds of the prior art, namely those according to formula (II). The global olfactive impression of the compounds of the present invention is generally that of musky odor compounds having a sweet and heavy connotation, close to that of the so-called polycyclic musks, quite unlike that of the compounds of formula (II) which show lighter and less tenacious olfactive notes.
The compounds of the invention can be present in the form of 4 stereoisomers in the pure state or as a mixture of the stereoisomers. The invention thus includes all these possible mixtures and all the possible individual isomers. As the olfactive note of each of these isomers can of course be different from that of the others, the odor of every possible isomer mixture can also change as a function of the content of any given diastereomer or enantiomer.
We have moreover been able to establish that within the above-identified preferred compounds of the invention according to formula (III), the best olfactive characteristics were represented in the isomers of the esters of the present invention derived from the alcohol (+)-(1S, 1xe2x80x2R)-1-(3xe2x80x2,3xe2x80x2-dimethyl- 1xe2x80x2-cyclohexyl)-1-ethanol, which is used as a starting product for the synthesis of some of the compounds of the invention.
As the most preferred compound of the invention, there is cited in particular 1-[(3,3-dimethyl-1-cyclohexyl)ethoxycarbonyl]methyl propanoate. This compound possesses a classical musky type odor, reminiscent of that of Galaxolide(copyright) (7,8-dihydro-4,6,6,7,8,8-hexamethyl-6H-cyclopenta[9]-2-benzopyrane; trademark of International Flavors and Fragrances, USA), and confers an olfactive impression which is that of a sweet and natural musky odor, with a velvety connotation, and which provides much volume. There is also found a light ambrette nuance which is accompanied by an undernote reminiscent of the odor of green fruits. When compared to the odor of the compounds according to the prior art, this compound of the invention develops a musky odor which is distinctly more tenacious and heavier than those of known compounds, which makes it particularly useful for the creation of base notes in perfumes and perfuming compositions of musky odor.
The above-described odor properties are best represented in the isomer of the configuration (1S, 1xe2x80x2R), namely (1S, 1xe2x80x2R)- 1-[(3xe2x80x2,3xe2x80x2-dimethyl-1xe2x80x2-cyclohexyl) ethoxycarbonyl]methyl propanoate, which renders this compound a choice ingredient of the invention.
Moreover, the mixtures containing a preponderant amount of this isomer together with its enantiomer or with its other stereoisomers give appreciated odor effects. Accordingly, mixtures containing a preponderant amount of this most preferred isomer of the invention are also a preferred embodiment of the invention.
The compounds of the invention can be used in practically all fields of modern perfumery. There can be cited here applications in fine perfumery, namely for the preparation of perfumes and colognes in which original olfactive effects can be obtained.
The compounds can also be used in functional perfumery. Non-limiting examples for this type application include soaps, bath and shower gels, shampoos and other hair care products, deodorants and an antiperspirants, air fresheners, liquid and solid detergents for the treatment of textiles, fabric softeners, or all purpose cleaners.
In these applications, the compounds (I) and (III) can be used alone or in admixture with other perfuming ingredients, solvents or adjuvants of current use in perfumery. The nature and the variety of these coingredients do not require a more detailed description here, which, moreover, would not be exhaustive, and the person skilled in the art will be able to choose the latter through its general knowledge and as a function of the nature of the product to be perfumed and of the desired olfactive effect. These perfuming ingredients belong to chemical classes as varied as alcohols, aldehydes, ketones, esters, ethers, acetates, nitrites, terpene hydrocarbons, sulfur- and nitrogen-containing heterocyclic compounds, as well as essential oils of natural or synthetic origin. A large number of these ingredients is moreover listed in reference textbooks such as the book of S. Arctander, Perfume and Flavor Chemicals, 1969, Montclair, N.J., USA, or its more recent versions, or in other works of similar nature.
The proportions in which the compounds according to the invention can be incorporated in the various products mentioned beforehand vary within a large range of values. These values depend on the nature of the article or product that one desires to perfume and the olfactive effect searched for, as well as on the nature of the coingredients in a given composition when the compounds of the invention are used in admixture with perfuming coingredients, solvents or adjuvants of current use in the art.
As an example, there can be cited typical concentrations of the order of 5 to 10%, or even 20%, by weight of these compounds relative to the weight of the perfuming composition in which it is incorporated. Far lower concentrations than those mentioned can be used when the compound (I) or (III) is directly applied for the perfuming of the various consumer products cited beforehand.
The compounds of the invention are generally prepared by esterification of an alcohol of formula (IV) below with the respective acid of formula (V), or an appropriate derivative of it. The reaction is illustrated in the following scheme I, in which the symbols R1 to R5 and X have the meaning indicated in formula (I). 
As an appropriate derivative of the acid (V), there can, for example, be cited the acid halides, like the chloride. Other appropriate derivatives are known to a person skilled in the art. In case one wants to synthesize an optically active compound of formula (I), there will be used the corresponding optically active alcohol of formula (IV) in the esterification reaction. According to a preferred embodiment of the invention, there will be used 1-(3,3-dimethyl-1-cyclohexyl)-1-ethanol or one of its enantiomers as starting alcohol for the preparation of the preferred compounds of the invention.
Where the acids of formula (V), respectively an appropriate derivative thereof, are not available or do not react as wanted, there can be used an alcohol of formula (VI) below in which X is an oxygen atom and the symbols R1 to R4 have the meaning indicated in formula (I), in an esterification reaction with an acid of formula (VII) in which R5 has the meaning given in formula (I), or, respectively, with an appropriate derivative of this acid, such as, for example, a halide. 
The alcohols of formula (VI) can be obtained by saponification of certain compounds of the invention of formula (I) in which X is an oxygen atom.
In the methods described above for the preparation of the compounds of the invention, the stereochemistry of the alcohols (IV) and (VI) is retained. The stereochemistry of the compounds of the invention is thus that of the alcohols used as starting products.
The specific reaction conditions will now be described in the following examples in which the abbreviations have the usual meaning in the art and the temperatures are given in degrees Celsius (xc2x0C); the NMR spectral data (chemical shift xcex4) are given in ppm relative to TMS as an internal standard. The invention will also be illustrated by examples describing the use of the compounds of the invention in perfumery.